Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 2 - Functions and Their Graphs - 2.2 The Graph of a Function - 2.2 Assess Your Understanding - Page 65: 27

Answer

(a) NO (b) $(4,-3)$ (c) $(14,2)$ (d) all real numbers except $x=6$ (e) $(-2,0)$ (f) $\left(0,-\frac{1}{3}\right)$

Work Step by Step

(a) To determine if $(3,14)$ is on the graph of $f$, substitute the $x$ and $y$ coordinates into the function. If the coordinates satisfy the function, then the point is on the graph of $f$. $f(x)=\dfrac{x+2}{x-6}$ $14=\dfrac{3+2}{3-6}$ $14\ne\dfrac{5}{-3} $ Thus, $(3, 14)$ is not on the graph of $f$. (b) Substitute $4$ to $x$ to obtain: $f(x)=\dfrac{x+2}{x-6}$ $f(4)=\dfrac{4+2}{4-6}$ $f(4)=-3$ The point on the graph are is $(4,-3)$ (c) Substitute $2$ to $f(x)$ then solve the equation to obtain: $f(x)=\dfrac{x+2}{x-6}$ $2=\dfrac{x+2}{x-6}$ $2(x-6)=x+2$ $2x-12=x+2$ $2x-x=2+12$ $x=14$ Therefore, the point on the graph is $(14,2)$ (d) The function is defined for all real numbers except when $x=6$ as it makes the denominator $0$. Hence, the domain is all real numbers except $x=6$ (e) To find the $x$-intercepts, subsitute $y=0$ to obtain: $f(x)=\frac{x+2}{x-6}$ $0=\frac{x+2}{x-6}$ $0=x+2$ $-2=x$ Therefore, the $x$ intercept is $(-2,0)$ (f) To find the $y$-intercept, set $x=0$ to obtain: $f(x)=\frac{x+2}{x-6}$ $y=\frac{0+2}{0-6}$ $y=-\frac{1}{3}$ Therefore, the $y$-intercept is $\left(0,-\frac{1}{3}\right)$
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